Steve McQueen 'upset' when he discovered slavery memoir

British film director Steve McQueen says he was "very upset" with himself for not knowing about Solomon Northup's 1853 memoir, 12 Years a Slave.

Speaking ahead of the European premiere of the film, which stars Chiwetel Ejiofor as Northup, McQueen said he came to realise no one he knew "knew about this book, and that's when I made it my passion to make this movie."